Aerodynamic spike nozzle



p 1966 JAMES E. WEBB 3,270,501

ADMINISTRATOR OF THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONAERODYNAMIC SPIKE NOZZLE Filed March 5, 1964 2 Sheets-Sheet 1 i I0 I I 4i -l2 I I I -"TI 2 'I I I ,\'I

I i I I s 2 I THOMAS E. Cows/.1. [20 .B. MA D/$0M INvIsNToRs I II I MiawTTOQNEVS Sept. 6, 1966 JAMES E. WEBB ADMINISTRATOR OF THE NATIONALAERONAUTICS AND SPACE ADMINISTRATION AERODYNAMIC SPIKE NOZZLE 2Sheets-Sheet 2 Filed March 5, 1964 Tue/was COWELJ- I20 .8. MflD/SOHINVENTORS ATTORNEYS United States Patent 3,270,501 AERODYNAMIC SPIKENOZZLE James E. Webb, Administrator of the National Aeronautics andSpace Administration, with respect to an invention of Thomas E. Cowelland Ira B. Madison Filed Mar. 5, 1964, Ser. No. 349,781 Claims. (Cl.60-35.6)

This invention relates to nozzles for propulsion engines and morespecifically to an improvement in a spike nozzle.

A spike nozzle generally comprises an annular injector and a physicalspike in the area surrounded by the injector. The spike is shapedgenerally like a cone, with the narrow part projecting from the centerof the injector. The propulsion gases from the injector impinge againstthe surface of the spike to provide thrust. One example of a spikenozzle can be seen in British Patent 885,489 of December 28, 1961; or inthe Handbook of Astronautical Engineering, published by McGraw-Hill(1961), section 20.335.

Some of the reasons a spike nozzle is preferred to a bell type nozzleare that it provides high thrust performance over a Wide range ofaltitudes. Also a spike nozzle can be made shorter than a bell typenozzle and yield equivalent thrust performance.

However a spike nozzle still presents a number of problems. The spikefor example is a disadvantage in a multistage rocket where a number ofnozzles are used. The spike increases the length of the rocket. Also theinbetween stage thrust structure, required due to the spikes length addsweight to the rocket.

Another problem is expense. It is expensive to fabricate a spike. Also,the material from which a spike is made is costly since the materialmust be capable of withstanding high temperatures.

Still another problem is cooling the spike and surrounding structure.The hot propulsion gases impinge against the spike and expose it to veryhigh temperatures. In addition, the heated spike in turn transfers partof its heat to the surrounding structure. This makes it necessary toprovide equipment to cool the spike and surrounding structure.

It is an object of this invention to provide a nozzle that can functionlike a spike nozzle but eliminates a number of the above mentioneddisadvantages.

It is therefore an object of this invention to provide a nozzle thatfunctions like a spike nozzle but eliminates the high temperature andheat transfer problems inherent in a conventional physical spike nozzle.

It is another object of this invention to provide a nozzle thatfunctions like a spike nozzle but is lighter, less expensive, and morecompact.

Essentially, the invention teaches how to construct a nozzle that formsa spike out of a fluid rather than out of physical hardware. Thus,eliminating the physical spike in prior art nozzles. The physical spikeis replaced by what may be termed an aerodynamic conical spike.

The nozzle is made with a central or inner injector that ejects apropulsion stream at a subsonic velocity, and an outer circumscribedannular injector that ejects, a propulsion stream at a supersonicvelocity contiguous to the subsonic propulsion stream. The supersonicpropulsion stream expands on leaving the nozzle and forms the subsonicpropulsion stream into a conical spike.

Thrust is derived as a result of the pressures produced on the nozzle bythe momentum flux of the supersonic and subsonic propulsion streamsreacting on the base of the nozzle.

There are a number of advantages in eliminating the physical spikestructure. There is a reduction of cooling equipment needed, becausethere is no spike to cool.

3,270,501 Patented Sept. 6, 1966 ice the theory is not understood, thata nozzle constructed as taught by this invention, will function withhigher efficiency (thrust per pound of propellant) than a comparablephysical spike nozzle of the prior art.

Other objects and advantages will appear from the following descriptionconsidered in conjunction with the accompanying drawings, in which:

FIG. 1 is a view of multi-stage rocket showing nozzles of this inventionas used in the various stages of a rocket;

FIG. 2 is a perspective cut-away view of a nozzle showing some of itsinternal structure;

FIG. 3 is a cross-sectional view of FIG. 2 taken in the direction ofarrows 33 showing the aerodynamic spike; and,

FIG. 4 is an enlarged view of a portion of FIG. 2, taken in thedirection of arrows 4--4, showing the interconnection of the fuel andoxidizer propellant inlets and the manifold construction.

Invention Referring to the drawings, there is shown in FIG. 1 amulti-stage rocket 2. Three stages 4, 6, and 8 are shown. For simplicityin explaining the invention, all stages will be assumed to be similar.Although the specific construction of each stage would depend on itsmission.

Each stage has a propulsion system that may include propellants such asfuel carried in tank 10 and an oxidizer carried in tank 12. Thepropellants are fed, by conventional means (not shown), to nozzle 14where they are mixed and combusted, and then ejected as subsonic andsupersonic propulsion streams to form a conical aerodynamic spike in amanner to be described.

Since the invention is in the nozzle, the following description willdescribe the nozzles construction and operation. The nozzle is shown inFIGURES 2, 3 and 4.

Fuel and oxidizer are fed into the nozzle through injector 18. Fuel fromtank 10 is fed into the nozzle through injector 18 by means in the formof a fuel inlet pipe 22 that leads into fuel manifold 24. The fuelpasses through openings 26 into combustion area 28. Oxidizer is fed intothe nozzle and into combustion area 28 by means of an oxidizer inletpipe 30 that leads into oxidizer manifold 32. The oxidizer then passesthrough a plurality of hollow tube members 34 that empty into combustionarea 28. Tubes 34 pass through manifold 28 to prevent the oxidizer frommixing with the fuel until both reach the combustion area. This isimportant where the propellants are hypergolic and would ignite oncontact.

The velocity of the combusted propellant is then increased to thesupersonic level. The propellant from combustion area 28 flows throughthroat portion 36 defined by inwardly approaching wall surfaces 38, 40where the throat increases the velocity of the propellants to thesupersonic level. The combusted propellants are then directed, by curvedwall extension 42, downwardly from the throat portion and ejected as asupersonic propulsion stream 43.

The subsonic stream is ejected by inner injector 20. Inner injector 20is circular and is carried within outer annular injector 1-8. Means areprovided to bleed a selected amount of combusted propellant fromcombustion area 28 of the outer injector and feed it to inner injector20. Cornbusted propellant flows to inner injector 20 through bleedopenings 44 in wall 38, then through a connecting passage 46 formed bywalls 48 and 50, and then into manifold 52 formed by walls 54, 56 andside 3 wall 42. The propellant is then ejected out of the injectorthrough a plurality of openings 58 in wall 56.

It will be noted that propellant fed to inner injector 24 does not passthrough a throat. This propellant in fact expands in manifold 52 andremains at a subsonic velocity level and it is thus ejected as subsonicvelocity stream 59, and formed into an aerodynamic conical spike by theaction of supersonic velocity stream 43.

The numbers and sizes of bleed openings 44 in annular injector 18 arechosen to provide a selected amount of bleed off. Where a rocket isconstructed for reuse, bleed openings 44 can be provided with adjustablevalves (not show-n) to vary the amount of propellant for a particularmission.

In terms of relative amount of fluid flow passing through the outer andinner injectors, it has been determined that satisfactory results can beobtained where about of the propellant stream is ejected from the innerinjector, and the remaining 95% ejected from the outer injector, or aratio of 1 in 20. It will be apparent that this amount can vary widelydepending on such factors as for example relative velocities, pressuresand masses of the fluid streams.

While inner injectors wall 56 is shown as dome shaped, this shape doesnot form the aerodynamic conical spike and is not necessary to theinvention. The aerodynamic conical spike is formed by the coaction ofthe supersonic and subsonic velocity propulsion streams. The spike wouldbe formed just as well if wall 56 were flat.

While propulsion fluid for inner injector 20 is obtained from combustionarea 28, it can be obtained from other sources. This is not critical tothe invention. As an example, the subsonic propulsion fluid may beobtained from the turbine exhaust (not shown), or a separate gasgenerator (not shown).

It will be noted that curved wall 42 does not extend beyond a plane thatwould pass through wall 40 forming the end of the nozzle. As a resultthe nozzle is quite compact and uses up little room.

Operation Propellants are fed to outer injector 18 of nozzle 14 throughfuel inlet 22 and oxidizer inlet 30. They are then combusted incombustion area 28. A major proportion of the combusted propellants thenpass through a throat portion 36 where the velocity is increased to thesupersonic level and are ejected from the nozzle.

A small portion of the combusted propellants are bled off throughopenings 44 in combustion area 28 and fed to inner injector 20 throughpassage 4-6 which leads into manifold 52 of the inner injector. Thisbled off propellant expands in manifold 52 thus lowering itstemperature. The bled off propellant is then ejected through openings 58in manifold 52 without passing through a throat so its velocity is inthe subsonic level.

On ejection, subsonic stream 59 is exposed to the high temperatureradiation from contiguous supersonic stream 43, and is compressed by theexpanding supersonic stream. This heats and speeds up the flow of thesubsonic stream and ultimately increases the eflective use of thesubsonic stream by providing increased thrust. In this flow, a boundarysurface 60 is formed between subsonic and supersonic fluid streams 43,59 where the static pressures of bot-h are equal, and forms the subsonicstream into an aerodynamic conical spike. This boundary 60 converges inthe rear direction (downward in FIG. 3) to a location where anaerodynamic throat is formed by supersonic stream 4-3 and causes thesubsonic stream to pass through the throat where its velocity willbecome sonic and then supersonic. This coaction of the two streamscauses the subsonic stream to produce increased pressure on the base ofthe inner injector.

As mentioned previously, thrust is derived as a result of pressuresproduced on the inner and outer injectors,

and the momentum flux of the main supersonic and subsonic streams.

It should be understood that it is not intended to limit this inventionto the herein disclosed form, but that the invention includes such otherforms or modifications as are embraced by the scope of the appendedclaims.

What is claimed is:

1. A method of providing thrust for a spike-free, shroud-free propulsionnozzle, comprising:

the step of expelling a first propulsion stream at a subsonic velocityin a selected amount from said nozzle; the step of expelling a secondpropulsion stream at a supersonic velocity from said nozzle; and,

the step of directing said supersonic propulsion stream contiguous tosaid subsonic propulsion stream, to form said subsonic propulsion streaminto the shape of an aerodynamic conical spike, and also forming anaerodynamic throat to increase the velocity of said subsonic stream to asupersonic level.

2. A method as set forth in claim 1 including the step of expelling saidfirst subsonic propulsion stream at a flow rate that is V of the flowrate of said second supersonic propulsion stream.

3. In a spike-free, shroud-free propulsion nozzle, the combinationcomprising:

a first injector constructed to eject a first propulsion stream at asubsonic velocity; :1 second injector circumscribing said first injectorand constructed to eject a second propulsion stream at a supersonicvelocity; and,

structure to direct said second propulsion stream contiguous to saidfirst subsonic propulsion stream to form said first propulsion streaminto an aerodynamic conical spike.

4. In a spike-free, shroud-free propulsion nozzle, the combinationcomprising: support structure;

an annular injector carried by said support structure;

said annular injector constructed with a throat portion to impartsupersonic velocity flow to said propulsion stream;

an inner injector, carried by said annular injector, within the areacircumscribed by said annular injector; means to feed a propulsionstream in a selected amount to said inner injector;

said inner injector constructed with an outlet to impart subsonicvelocity flow to said propulsion stream; and,

said annular ejectors throat including structure positioned to directsaid supersonic velocity propulsion stream contiguous to said subsonicvelocity propulsion stream to form said subsonic velocity stream into anaerodynamic conical spike.

5. In a propulsion nozzle, the combination comprising: supportstructure;

an annular injector carried by said support structure;

said annular injector constructed with a'combustion area leading to athroat portion; means to feed propellants to said annular injectorscombustion area to create a propulsion stream;

said throat portion of said annular injector constructed to impartsupersonic velocity flow to said propulsion stream;

an inner injector, carried by said annular injection,

within the area circumscribed by annular injector; means to feed apropulsion stream in a selected amount to said inner injector;

said inner injector constructed with an outlet to impart subsonicvelocity flow to said propulsion stream; and,

said annular ejectors throat including structure positioned to directsaid supersonic velocity propulsion stream contiguous to said subsonicvelocity propulsion stream, to form said subsonic velocity fluidpropulsion stream into an aerodynamic conical spike and also forming anaerodynamic throat to increase the velocity of the subsonic stream to asupersonic level.

6. A device as set forth in claim 5 wherein saidnozzle is constructed toeject 5% of the propulsion stream from said inner injector and 95% ofthe propulsion stream from said annular injector.

7. In a propulsion nozzle, the combination comprising: supportstructure;

an annular injector carried by said support structure;

said annular injector constructed with a combustion area leading to athroat portion, said combustion area and throat portion including acommon end wall; means to feed propellants to said annular injectorscombustion area to create a propulsion stream;

said throat portion of said first injector constructed to impartsupersonic velocity to flow to said propulsion stream;

an inner injector, carried by said annular injector, within the areacircumscribed by annular injector;

means connected to said annular injector to feed a propulsion stream ina selected amount to said inner injector;

said inner injector constructed With an outlet to impart subsonicvelocity flow to said propulsion stream and,

said annular ejectors throat including structure that ends short of aplane passing through said end wall and positioned to direct saidsupersonic velocity propulsion stream contiguous to said subsonicvelocity propulsion stream to form said subsonic velocity propulsionstream into an aerodynamic conical spike, and also forming anaerodynamic throat to increase the velocity of said subsonic stream to asupersonic level.

8. In a propulsion nozzle, the combination comprising:

support structure;

an annular injector carried by said support structure;

said annular injector constructed with a combustion area leading to athroat portion;

means to feed propellants to said annular injectors combustion area tocreate a propulsion stream;

said throat portion of said first injector constructed to impartsupersonic velocity to flow of said propulsion stream;

an inner injector, carried by said annular injector, within the areacircumscribed by annular injector; means to obtain combusted propellantfrom said annular injectors combustion area and to feed a selectedamount to said inner injector; said inner injector constructed with anoutlet to impart subsonic velocity flow to said propulsion stream; and,said annular ejectors throat including structure positioned to directsaid supersonic velocity propulsion stream contiguous to said subsonicvelocity propulsion stream, to form said subsonic velocity propulsionstream, into an aerodynamic conical spike, and also forming anaerodynamic throat to increase the velocity of said subsonic stream to asupersonic level. 9. A device as set forth in claim 8, wherein saidmeans to obtain said combusted propellant for said inner injectorincludes a passage interconnection between said combustion area andinner injector, and said combustion area and inner injector are providedwith openings to permit flow of combusted propellant in a selectedamount from said combustion area to said inner injector.

10, In a propulsion nozzle: means to eject 5% of the propulsion streamcentrally from the propulsion nozzle at a subsonic velocity; meanssurrounding said first means, to eject 95% of the propulsion stream atsupersonic velocity, and; means to direct said supersonic propulsionstream contiguous to said subsonic propulsion stream, to form saidsubsonic velocity propulsion stream into an aero dynamic conical spike.

References Cited by the Examiner UNITED STATES PATENTS 1,375,60 1 4/1921Morize -35.6 2,922,277 1/1960 Bertin 24423 3,112,612 12/1963 Adamson60-35.6 3,127,739 4/1964 Miller 60-35.6 3,167,912 2/ 1965 Ledwith 60-3563,216,191 11/1965 Madison 60-356 FOREIGN PATENTS 570,334 2/1959 Canada.

MARK NEWMAN, Primary Examiner.

RALPH D. BLAKESLEE, Examiner.

1. A METHOD OF PROVIDING THRUST FOR A SPIKE-FREE, SHROUD-FREE PROPULSIONNOZZLE, COMPRISING: THE STEP OF EXPELLING A FIRST PROPULSION STREAM AT ASUBSONIC VELOCITY IN A SELECTED AMOUNT FROM SAID NOZZLE; THE STEP OFEXPELLING A SECOND PROPULSION STREAM AT A SUPERSONIC VELOCITY FROM SAIDNOZZLE; AND, THE STEP OF DIRECTING SAID SUPERSONIC PROPULSION STREAMCONTIGUOUS TO SAID SUBSONIC PROPULSION STREAM, TO FORM AND SUBSONICPROPULSION STREAM INTO THE SHAPE OF AN AERODYNAMIC CONICAL SPIKE, ANDALSO FORMING AN AERODYNAMIC THROAT TO INCREASE THE VELOCITY OF SAIDSUBSONIC STREAM TO A SUPERSONIC LEVEL.
 3. IN A SPIKE-FREE, SHROUD-FREEPROPULSION NOZZLE, THE COMBINATION COMPRISING: A FIRST INJECTORCONSTRUCTED TO EJECT A FIRST PROPULSION STREAM AT A SUBSONIC VELOCITY, ASECOND INJECTOR CIRCUMSCRIBING SAID FIRST INJECTOR AND CONSTRUCTED TOEJECT A SECOND PROPULSION STREAM AT A SUPERSONIC VELOCITY; AND,STRUCTURE TO DIRECT SAID SECOND PROPULSION STREAM CONTIGUOUS TO SAIDFIRST SUBSONIC PROPULSION STREAM TO FORM SAID FIRST PROPULSION STREAMINTO AN AERODYNAMIC CONICAL SPIKE.